Re: [PATCH] s390: cio: fix two use-after-free bugs in device.c
在 2020/11/20 15:55, Cornelia Huck 写道: On Fri, 20 Nov 2020 15:48:49 +0800 Qinglang Miao wrote: put_device calls release function which do kfree() inside. So following use of sch would cause use-after-free bugs. Fix these by simply adjusting the position of put_device. Fixes: 37db8985b211 ("s390/cio: add basic protected virtualization support") Fixes: 74bd0d859dc3 ("s390/cio: fix unlocked access of online member") Reported-by: Hulk Robot Signed-off-by: Qinglang Miao --- drivers/s390/cio/device.c | 6 +++--- 1 file changed, 3 insertions(+), 3 deletions(-) diff --git a/drivers/s390/cio/device.c b/drivers/s390/cio/device.c index b29fe8d50..69492417b 100644 --- a/drivers/s390/cio/device.c +++ b/drivers/s390/cio/device.c @@ -1664,10 +1664,10 @@ void __init ccw_device_destroy_console(struct ccw_device *cdev) struct io_subchannel_private *io_priv = to_io_private(sch); set_io_private(sch, NULL); - put_device(>dev); - put_device(>dev); dma_free_coherent(>dev, sizeof(*io_priv->dma_area), io_priv->dma_area, io_priv->dma_area_dma); + put_device(>dev); + put_device(>dev); That change looks reasonable. kfree(io_priv); } @@ -1774,8 +1774,8 @@ static int ccw_device_remove(struct device *dev) ret, cdev->private->dev_id.ssid, cdev->private->dev_id.devno); /* Give up reference obtained in ccw_device_set_online(). */ - put_device(>dev); spin_lock_irq(cdev->ccwlock); + put_device(>dev); As the comment above states, the put_device() gives up the reference obtained in ccw_device_set_online(). There's at least one more reference remaining (held by the caller of the remove function). Moving the put_device() does not fix anything here. Hi, Cornelia Sorry for the delayed reply. Your suggestion is reasonable, there is a mistake in this patch for I didn't notice that there would be at least one more reference remaining. So I sent a new patch only to move put_device after dma_free_coherent. I put the link as below: https://lore.kernel.org/lkml/20201201063150.82128-1-miaoqingl...@huawei.com/ Thanks! } ccw_device_set_timeout(cdev, 0); cdev->drv = NULL; .
Re: [PATCH] s390: cio: fix two use-after-free bugs in device.c
On Fri, 20 Nov 2020 15:48:49 +0800 Qinglang Miao wrote: > put_device calls release function which do kfree() inside. > So following use of sch would cause use-after-free bugs. > > Fix these by simply adjusting the position of put_device. > > Fixes: 37db8985b211 ("s390/cio: add basic protected virtualization support") > Fixes: 74bd0d859dc3 ("s390/cio: fix unlocked access of online member") > Reported-by: Hulk Robot > Signed-off-by: Qinglang Miao > --- > drivers/s390/cio/device.c | 6 +++--- > 1 file changed, 3 insertions(+), 3 deletions(-) > > diff --git a/drivers/s390/cio/device.c b/drivers/s390/cio/device.c > index b29fe8d50..69492417b 100644 > --- a/drivers/s390/cio/device.c > +++ b/drivers/s390/cio/device.c > @@ -1664,10 +1664,10 @@ void __init ccw_device_destroy_console(struct > ccw_device *cdev) > struct io_subchannel_private *io_priv = to_io_private(sch); > > set_io_private(sch, NULL); > - put_device(>dev); > - put_device(>dev); > dma_free_coherent(>dev, sizeof(*io_priv->dma_area), > io_priv->dma_area, io_priv->dma_area_dma); > + put_device(>dev); > + put_device(>dev); That change looks reasonable. > kfree(io_priv); > } > > @@ -1774,8 +1774,8 @@ static int ccw_device_remove(struct device *dev) > ret, cdev->private->dev_id.ssid, > cdev->private->dev_id.devno); > /* Give up reference obtained in ccw_device_set_online(). */ > - put_device(>dev); > spin_lock_irq(cdev->ccwlock); > + put_device(>dev); As the comment above states, the put_device() gives up the reference obtained in ccw_device_set_online(). There's at least one more reference remaining (held by the caller of the remove function). Moving the put_device() does not fix anything here. > } > ccw_device_set_timeout(cdev, 0); > cdev->drv = NULL;
[PATCH] s390: cio: fix two use-after-free bugs in device.c
put_device calls release function which do kfree() inside. So following use of sch would cause use-after-free bugs. Fix these by simply adjusting the position of put_device. Fixes: 37db8985b211 ("s390/cio: add basic protected virtualization support") Fixes: 74bd0d859dc3 ("s390/cio: fix unlocked access of online member") Reported-by: Hulk Robot Signed-off-by: Qinglang Miao --- drivers/s390/cio/device.c | 6 +++--- 1 file changed, 3 insertions(+), 3 deletions(-) diff --git a/drivers/s390/cio/device.c b/drivers/s390/cio/device.c index b29fe8d50..69492417b 100644 --- a/drivers/s390/cio/device.c +++ b/drivers/s390/cio/device.c @@ -1664,10 +1664,10 @@ void __init ccw_device_destroy_console(struct ccw_device *cdev) struct io_subchannel_private *io_priv = to_io_private(sch); set_io_private(sch, NULL); - put_device(>dev); - put_device(>dev); dma_free_coherent(>dev, sizeof(*io_priv->dma_area), io_priv->dma_area, io_priv->dma_area_dma); + put_device(>dev); + put_device(>dev); kfree(io_priv); } @@ -1774,8 +1774,8 @@ static int ccw_device_remove(struct device *dev) ret, cdev->private->dev_id.ssid, cdev->private->dev_id.devno); /* Give up reference obtained in ccw_device_set_online(). */ - put_device(>dev); spin_lock_irq(cdev->ccwlock); + put_device(>dev); } ccw_device_set_timeout(cdev, 0); cdev->drv = NULL; -- 2.23.0